.site-error{
    position: relative;
    width: 800px;
    height: 800px;
    margin: auto;
    background: url("../img/404.png");
}
.site-error .alert,.site-error h1{
    display: none;
}
.site-error .back{
    position: absolute;
    display: block;
    padding: 5px 10px;
    background-color: #ffc926;
    color: #ffffff;
    top: 480px;
    left: 351px;
    text-decoration: none;
}